Due to the inherent complexity of biological applications that more often than not include fluids and structures interacting together, the development of computational fluid–structure interaction models is necessary to achieve a quantitative understanding of their structure and function in both health and disease. The functions of biological structures usually include their interactions with the surrounding fluids. Hence, we contend that the use of fluid–structure interaction models in computational studies of biological systems is practical, if not necessary. The ultimate goal is to develop computational models to predict human biological processes. These models are meant to guide us through the multitude of possible diseases affecting our organs and lead to more effective methods for disease diagnosis, risk stratification, and therapy. This review paper summarizes computational models that use smoothed-particle hydrodynamics to simulate the fluid–structure interactions in complex biological systems.

Nodular lymphoid hyperplasia (NLH) is characterized by the growth of multiple discrete small submucosal nodules specifically confined to the lamina propria and superficial submucosa layers of the intestinal wall. Gastric and rectal involvement of NLH is exceedingly rare. To date, few case reports have described diffuse NLH presenting with multiple submucosal lymphomatous polyposis occurring in the rectum.Our patient is a 39-year-old morbidly obese Hispanic female who presented to the gastroenterology clinic complaining of intermittent hematochezia for the past six months. Colonoscopy showed diffuse nodularity in the sigmoid colon and rectal mucosa, extending 20 cm from the rectal verge. Rectal biopsies revealed moderate active chronic inflammation predominantly of lymphoplasmacytic cells with areas of lymphoid hyperplasia and focal surface ulceration. Immunohistochemistry stains revealed reactive lymphoid hyperplasia (RLH).The NLH is a risk factor for extraintestinal and intestinal lymphomas. When encountering lymphoid hyperplasias, the possibility of malignancy must always be considered. It is crucial to monitor patients with NLH via capsule endoscopies, small bowel series, and colonoscopy for surveillance of new lesions in light of the potential for malignancy.

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